This invention generally relates to a counterpulsation device and more particularly to a counterpulsation device that operates without the use of compressed air.
Various counterpulsation devices are known and used in the medical field. Counterpulsation devices typically include inflatable cuffs that are placed about selected portions of a patient""s body. The inflatable cuffs are typically placed about the calves, thighs and buttocks of a patient. The cuffs are inflated sequentially in a distal to proximal order during diastole. The inflation of the cuffs is timed to provide a second, pressurized pulse of blood flow to all organs above the buttocks cuff when the heart is normally resting between beats. The extra pulse of blood flow has been demonstrated to relieve angina pectoris, to raise cardiac output thereby improving the perfusion of organ beds and to enhance renal, cardiac and cerebral circulation.
In typical arrangements a compressed air source is used to inflate the cuffs and a vacuum pump is used to evacuate the cuffs as needed.
The currently available counterpulsation systems have several shortcomings and drawbacks, mainly because they require the use of compressed air. Compressed air is disadvantageous because it must be carefully managed or it introduces potential problems. Systems using compressed air can become overly pressurized because of a malfunction or blockage in the compressor or an associated accumulator. Overly high pressure conditions must be minimized to avoid subjecting the patient to excessive pressure when inflating the cuffs. Under extreme circumstances, excess pressure buildup introduces the possibility of having a portion of the system, such as a hose or the compressor housing, rupture unexpectedly.
Typical compressors also render conventional systems undesirably noisy, which makes them less than ideal for a hospital or clinic setting. The compressors and reservoirs are also relatively large and cumbersome, which decreases their ability to be readily relocated. The compressed air systems also require components such as vacuum pumps, which introduce additional cost, noise, complexity, and further maintenance issues.
Conventional systems require frequent maintenance because filters and other components must be replaced, especially in a counterpulsation application where the overall machine may be used continuously for many hours. Additionally, compressed air introduces the possibility of condensation build up within the system, which can interfere with proper valve, cuff, and other component operation to further exacerbate the maintenance issues.
All of the above drawbacks contribute to a major shortcoming of conventional systems, which is that they are not portable and useable in different clinical or hospital settings. Another drawback associated with some of the available systems is that they are not versatile enough to provide counterpulsation therapy for a wide enough variety of applications.
There is a need for a counterpulsation device that provides the capabilities of the pressure driven systems that are currently available while having the advantage of not including the use of pressurized or compressed gas. This invention overcomes the shortcomings and drawbacks discussed above and provides a system that is versatile in administering counterpulsation therapy without the use of pressurized or compressed air.
In general terms, this invention is a counterpulsation device that operates without the use of compressed air or pressurized gas to create tissue compression. The invention includes several basic parts. At least one inflatable cuff is provided that is adapted to be placed about a selected portion of the patient""s body. A conduit connects the inflatable cuff to an air moving device so that noncompressed air can be transferred from the air moving device to the cuff through the conduit to inflate the cuff. This conduit also performs a second function of allowing the air to leave the cuff, which deflates the cuff. A series of valves are associated with the conduit to selectively control whether air is supplied to or withdrawn from the inflatable cuff.
The air moving device preferably is a cylinder having a piston that moves through the cylinder to move air from within the cylinder through the conduit and into or out of the cuff as desired. The piston preferably moves through the cylinder through the use of a linear servo actuator that is controlled by an appropriately programmed electronic controller so that the inflation of the cuff is timed with portions of the patient""s EKG signal and peripheral plethysmographic wave.
In the preferred embodiment there are two cuffs that are placed about the lower portion or calves of the patient""s legs. There also preferably are two cuffs to be placed about the patient""s thighs and a cuff that is placed about the patient""s buttocks.
In an alternative application, the cylinder draws from a reservoir of specific gas or liquid with special characteristics that permit more thorough and rapid volume/pressure changes within the cuffs.
In still another embodiment, a multi-wave, non-distensible unit encases the entire lower hemi-corpus. In this example the unit is segmented into an ankle, calf, thigh, and buttocks section. Tissue compression is applied to each component sequentially without direct material tissue interaction and thus avoids cutaneous irritation which may otherwise occur with continuous cuff inflation and deflation
In an alternative embodiment, the apparatus producing the tissue compression to provide augmentation may be applied uniquely on every other heart beat, every second beat, or every third beat, depending on which sequence produces the most augmentation.
The various features and advantages of this invention will become apparent to those skilled in the art from the following description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.